Gaskets are used in a variety of applications, for example in appliances, such as refrigerators and freezers, each requiring a flexible gasket for sealing the area between the door and appliance body. One of the most commonly used materials for the production of gaskets is polyvinyl chloride (PVC). PVC gaskets become brittle at low temperatures and cracking becomes a problem, and installation at lower temperatures is also difficult. Also, an unpleasant odor is present during compounding and extrusion of PVC, and when the finished gaskets are removed from packaging prior to installation. Moreover, PVC is not considered an environmentally friendly material because it involves the use of the following: vinyl chloride monomer production, phthalate plasticizers, heat stabilizers, and processing lubricants that may contain heavy metals. In addition, PVC-based gaskets, or other products, may give rise to disposal concerns as well as potential release of toxic materials in the event of incineration. Therefore, there is a need for a material to replace PVC-based profiles, particularly those used in large home appliances such as refrigerator and freezer gaskets, washing machines, dryers and dishwashers, and which satisfies the required specifications, and has improved processability and environmental friendliness. Other applications of such polymeric materials could include, for example, molded articles, overmolded articles, and tubing.
Profiles made of thermoplastics, manufactured by the profile extrusion process, are known. The design of compositions of thermoplastic elastomers (TPE) used for profiles demands that several properties be balanced. These include low viscosity at processing shear rates, ability to freeze quickly as the profile leaves the die so dimensional stability can be maintained, a certain compression set for elastic recovery under transportation and use conditions, ability to heat weld, and a certain softness for better sealing properties. Production of TPEs for profile applications has required rheological modification steps, such as peroxide modification of the thermoplastic elastomer or dynamic vulcanization, or use of expensive ingredients such as styrene block copolymer (SBC)-rich compounds, in order to balance the required end-use properties. Therefore, there remains a need for a TPE for profile use that meets all of the specifications to replace PVC-based profiles, while simplifying production and design of the TPEs.